An inverter converts battery DC power into AC power your home loads can use. Sizing it badly creates a frustrating system: plenty of energy stored, but not enough power to run the loads you care about.
The two ratings
Continuous output
This is what the inverter can provide steadily. Add up the loads that may run at the same time.
Surge output
This is the short burst needed by motors, pumps, compressors, and some tools. A refrigerator, freezer, sump pump, or air conditioner may need more startup power than its running watts suggest.
120V and 240V
Many portable systems provide 120V loads only. Some home loads require 240V or split-phase service: EV charging, many well pumps, dryers, ranges, and some HVAC equipment.
Do not assume a battery can run a large appliance because its watt-hour capacity looks big. Voltage, output, wiring, and transfer equipment matter.
Pure sine wave
For household electronics and motor loads, pure sine wave output is the normal target. Modified sine wave inverters can create compatibility, noise, heat, or performance problems.
Decision section
Ask:
- What is the largest load I want to run?
- What loads can run at the same time?
- Which loads have startup surge?
- Do I need 240V?
- Does the inverter support the transfer or subpanel design?
- What does the manufacturer allow?
If any answer includes panel integration, permanent wiring, or large 240V loads, bring in a qualified electrician.
For upstream load planning, read Watts, kWh, and Loads . For system safety, read Solar Electrical Safety .
